1. Field of the Invention
The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus for reproducing an image of a document.
2. Description of the Prior Art
In one prior art apparatus of this type, a size of a copy sheet to be fed is designated and a size of a document sheet detected by an appropriate method is compared with the copy sheet size to automatically set a copying magnification. However, when an image area in the document sheet is extremely smaller than the document sheet size, a blank area is created in a copy image and it makes the copy image hard to view.
In another prior art apparatus of this type, eraser means is provided to prevent deposition of toner to edges of a reproduced image. However, when an image exists in the edge areas on the document sheet and those areas should be copied, the information of the edges may be lost depending on illumination by the eraser means.
In other prior art apparatus of this type, a light is irradiated to a document sheet placed at a reference position on a document sheet table and an image is formed by a light reflected from the document sheet, and a size of the copy sheet loaded is detected to control an eraser in order to prevent deposition of unnecessary toner. However, if the document sheet is placed at a position different from the reference position on the document sheet table, the toner is deposited on undesired areas of the copy sheet.
In the prior art apparatus of this type, when a thick document such as a book is to be copied, the book is mounted on the document sheet table and the book is pressed by a document sheet pressing plate or other means to eliminates a gap between the original sheet table and the book, and the copy operation is carried out. However, even if the operator presses the book, a folding line of the book is not eliminated and undue pressure may be applied to the document sheet table and the document sheet table may be deformed. If the user carries out the copy operation without using the document sheet pressing plate, toner is attached to the edges and the folding line and the quality of the reproduced image is very poor.